JP2949945B2 - Transmission line switching circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission line switching circuit,
In particular, the present invention relates to a transmission line switching circuit that switches between two transmission lines having different phases.

[0002]

2. Description of the Related Art Conventionally, this type of transmission line switching circuit is shown in FIG.
The configuration is as shown in FIG. Transmission line monitoring signal insertion circuit 1
The clock signal 102 inserts the transmission path monitoring signal output from the counter 3 into the data signal 101 from the transmission path 1 and outputs the data signal 107 with the transmission path monitoring signal to the selector 11. The counter 3 receives the clock signal 102 and the frame pulse signal 103 from the transmission line 1 and
The above-described transmission path monitoring signal to be inserted at a predetermined pulse position of the data signal 101 is output. The transmission line monitoring signal insertion circuit 2 and the counter 4 are on the transmission line 2 side and have the same functions as described above. The selector 11 connects each signal on the transmission path 1 with the transmission path 2
One of these signals is selected by a switching signal 109 from an external transmission line monitoring device. That is, normally, transmission line 1
When the switching signal 109 is inverted due to the selection of the transmission line 1 and the transmission line 1 failure, the switching to the transmission line 2 is performed immediately.

The transmission line monitoring signal detection circuit 9 uses a detection transmission line monitoring signal output from the counter circuit 10 to output a data signal 130 with a transmission line monitoring signal from the selector 11.
Transmission line monitoring signal is detected and the transmission line monitoring alarm signal 1
33 and a data signal 134 are output. That is, the transmission path monitoring signal including the selector 11 is monitored by the transmission path monitoring signal, and if the transmission path monitoring signal is abnormal, the transmission path monitoring alarm signal 133 is issued.

[0004]

As described above, in the conventional example, since the transmission path is switched immediately after the switching signal 109 is inverted, the data of the first frame of the selected data signal after the switching is transmitted between the transmission paths. If the phases are different, the data before and after the switching will be linked, so that the transmission path monitoring signal inserted before the selector 11 may not be detected depending on the switching timing. For this reason, there is a problem that the transmission path monitoring alarm signal 133 gives a false alarm.

[0005]

A transmission line switching circuit according to the present invention receives a first frame pulse signal and a first clock signal from a first transmission line and outputs a first transmission line monitoring signal. A first counter that performs
The first clock signal to the first data signal.
A first transmission line monitoring signal insertion circuit that inserts the transmission line monitoring signal and outputs a data signal with the first transmission line monitoring signal;
A second counter for inputting a second frame pulse signal and a second clock signal from the second transmission path and outputting a second transmission path monitoring signal; and a second counter for outputting the second transmission path monitoring signal from the second transmission path. A second transmission path supervisory signal insertion circuit for inserting the second transmission path supervisory signal into the data signal by the second clock signal and outputting a data signal with a second transmission path supervisory signal; A data signal with a path monitoring signal, the first clock signal and the first frame pulse signal, and a data signal with the second transmission path monitoring signal, the second clock signal and the second frame pulse signal. A first selector for selecting one of the inputs and outputting the selected one,
A third counter that inputs a third clock signal and a third frame pulse signal output from the selector and outputs a third transmission path monitoring signal, and a third transmission path that the first selector outputs A transmission path for detecting a transmission path monitoring signal inserted in a data signal with a monitoring signal using the third clock signal and the third transmission path monitoring signal and outputting a transmission path monitoring alarm signal and a data signal to the outside. A monitoring signal detection circuit, a second selector that inputs the first frame pulse signal and the second frame pulse signal, and selects a transmission path side opposite to a transmission path side selected by the first selector; A switching input signal input from the outside is latched by the output signal of the second selector, output to the first selector as a switching output signal, and simultaneously detecting the transmission path monitoring signal as a reset signal. It includes a latch circuit for output to the road, and an inverter circuit for inverting the switching output signal output to the second selector.

[0006]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. The transmission path monitoring signal insertion circuit 1 inserts the transmission path monitoring signal output from the counter 3 into the data signal 101 from the transmission path 1 by the clock signal 102 and outputs the data signal 107 with the transmission path monitoring signal to the selector 8. . The counter 3 receives the clock signal 102 and the frame pulse signal 103 from the transmission line 1 and outputs the above-described transmission line monitoring signal to be inserted at a predetermined pulse position of the data signal 101. Transmission line monitoring signal insertion circuit 2 and counter 4
Side has the same function as described above. The selector 8 selects one of the signals on the transmission path 1 and the signals on the transmission path 2 based on the switching output signal 118 output from the latch circuit 6. That is, normally, the transmission line 1 side is selected, and when the transmission line 1 side fails and the switching output signal 118 is inverted, the transmission line 1 side is switched.

A transmission line monitoring signal detection circuit 9 detects a transmission line monitoring signal included in the data signal 115 with a transmission line monitoring signal from the selector 8 based on a detection transmission line monitoring signal output from the counter circuit 10 and externally. To output a transmission path monitoring alarm signal 119 and a data signal 120. That is, the transmission line monitoring signal including the selector 8 is monitored by the transmission line monitoring signal, and if the transmission line monitoring signal is abnormal, the transmission line monitoring alarm signal 119 is issued. The selector 5 receives the frame pulse signal 103 of the transmission line 1 and the frame pulse signal 106 of the transmission line 2 and selects one of them according to the switching output signal 118 inverted by the inverter circuit 7. That is, the transmission line side opposite to the selection of the selector 8 is selected. The latch circuit 6 receives a switching input signal 109 from an external transmission path monitoring device and an output signal of the selector 5, latches the switching input signal 109 with the output signal of the selector 5, and outputs the switching output signal 118 8 and at the same time, to the transmission line monitoring signal detection circuit 9 as a reset signal.

Next, the operation will be described with reference to FIG. FIG. 2 is a time chart for explaining the switching operation of the present embodiment. First, it is assumed that the selector 8 has selected the transmission path 1 as an initial state. At this time, the selector 5 has selected the frame pulse signal 106 of the transmission path 2. Figures (a) to (d)
Indicates the states of the frame pulse signals of the transmission paths 1 and 2 having different phases and the state of the data signal with the transmission path monitoring signal. A transmission path monitoring signal is inserted for each frame of the data signal with the transmission path monitoring signal. When the switching input signal 109 shown in FIG. 7E is inverted due to a failure in the transmission line 1, the switching output signal 108 shown in FIG. Since it is latched by the frame pulse 106 of the path 2 and output as the switching output signal 108, it is inverted at the illustrated delay timing.

By the inversion of the switching output signal 108, the selector 8 selects and switches the transmission line 2 side. Figures (g) and (h)
Indicates a frame pulse signal 117 output from the selector 8 and a data signal 115 with a transmission path monitoring signal.
FIG. 9H shows a transmission line monitoring alarm signal 119 output from the transmission line monitoring signal detection circuit 9. This detection output signal is output at the next frame pulse and reset at the same time. However, when the selector 8 is switched, the switching output signal 108 is input as a reset signal, and the detection output signal of the previous frame is reset.

[0010]

As described above, according to the present invention, the switching of the transmission path is switched in synchronization with the frame pulse, so that the transmission path monitoring signal included in the frame before and after the switching can be reliably detected. This has the effect of preventing the occurrence of false alarms.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of the present embodiment.

FIG. 2 is a time chart for explaining a switching operation of the embodiment.

FIG. 3 is a block diagram showing a configuration of a conventional example.

[Explanation of symbols]

 1, 2 transmission line monitoring signal insertion circuit 3, 4, 10 counter 5, 8 selector 6 latch circuit 7 inverter circuit 9 transmission line monitoring signal detection circuit 101, 104, 120 data signal 102, 105, 116 clock signal 103, 106, 117 Frame pulse signal 109 Switching input signal 119 Transmission line monitoring alarm signal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04L 1/22 H04B 1/74 H04Q 11/04

Claims (1)

(57) [Claims] A first counter for receiving a first frame pulse signal and a first clock signal from a first transmission line and outputting a first transmission line monitoring signal; and the first transmission line. A first transmission path supervisory signal insertion circuit for inserting the first transmission path supervisory signal into the first data signal from the first clock signal according to the first clock signal and outputting a data signal with the first transmission path supervisory signal; A second counter for inputting a second frame pulse signal and a second clock signal from the second transmission path and outputting a second transmission path monitoring signal; and a second counter for outputting the second transmission path monitoring signal from the second transmission path. A second transmission path supervisory signal insertion circuit for inserting the second transmission path supervisory signal into the data signal by the second clock signal and outputting a data signal with a second transmission path supervisory signal; Data signal with path monitoring signal, the first clock signal A first signal for inputting the first frame pulse signal, the data signal with the second transmission path monitoring signal, the second clock signal and the second frame pulse signal, and selecting and outputting one of the signals; A selector, a third counter that inputs a third clock signal and a third frame pulse signal output from the first selector and outputs a third transmission path monitoring signal, and an output of the first selector A transmission line monitoring signal inserted in the data signal with the third transmission line monitoring signal is detected by the third clock signal and the third transmission line monitoring signal, and a transmission line monitoring alarm signal and a data signal are sent out. A transmission line monitoring signal detection circuit for outputting the first frame pulse signal and the second frame pulse signal, and a transmission line side opposite to a transmission line side selected by the first selector. The second to select
And a switching input signal input from the outside, latched by the output signal of the second selector, output to the first selector as a switching output signal, and simultaneously output to the transmission path monitoring signal detection circuit as a reset signal. A transmission line switching circuit, comprising: a latch circuit; and an inverter circuit that inverts the switching output signal and outputs the inverted signal to the second selector.